A. Field of the Invention
The present invention relates to bases or supports for vertically extending or elevating structures, and, in particular, to portable or temporary footings or bases for the same.
B. Problems in the Art
A wide variety of ways to support vertically extending structures have been developed over time. Special considerations come into play for structures that extend substantial distances vertically, and further, when the structures may experience forces that tend to tip the structures, such as wind.
Structure and stability issues become even more acute in situations where support for the vertical structure is desired to be portable or temporary. If the foundation or base cannot utilize any permanent footings in the ground, a primary source for providing stability to a vertical structure does not exist.
A few specific examples will illustrate this point. Situations exist where it would be desirous to have high-powered, wide area lighting, but on a temporary basis. The practical problems are, first, how does one transport such a system, especially when it is desirable to have the lights elevated to substantial distances vertically in the air; and second, how does one support and keep stable such elevated lighting fixtures through a variety of environmental conditions such as winds?
One situation where wide-area portable lighting is desired is with regard to construction sites. There are existing systems for temporary construction site lighting which tend to be on portable trailers or trucks. Lighting fixtures can be installed on foldable or extendible booms or frames. These types of conventional portable lighting units generally each require a separate vehicle to transport them from location to location. Also, they tend to be able to elevate the lights no more than perhaps 15′ to 35′. This does not allow for large area lighting. Additionally, because the lights are relatively close to the ground, glare problems can exist for workers and for traffic. Still further, many of these lighting systems are limited in height and number of lights, because of limitations of the base. Basically, existing systems tend to be no more than just a few light fixtures on a scaffold or foldable tower that does not extend very far into the air.
Some truck-based systems with larger, extendible booms exist. For example, U.S. Pat. Nos. 4,423,471, 4,712,167, 5,207,747, and 5,313,378 disclose high-powered lighting fixtures which can be extended much higher in the air (much over 30′) and are portable because they are mounted to trucks. However, such systems are expensive, both in original cost and operation, especially for areas such as constructions sites. Also, the trucks on which the fixtures are mounted would be out of use during the time the portable lighting was in use.
Therefore, a system has been developed which essentially consists of a transportable base that can be transported on conventional over-the-road trucks such as semi-trailers, can be manipulated by forklifts, and which can support a substantial sized light pole and array of light fixtures. Such a system is disclosed in commonly owned and co-pending U.S. Ser. No. 08/853,173. This system is relatively low-cost, can support a very tall vertical structure, and is portable. However, it is not adjustable in a variety of situations.
For example, such a base is pre-manufactured and fixed in perimeter size and in weight. It is also fixed in all dimensions and characteristics. If selected for a certain use, it may not be functional for another use. It may support a 50′ pole with five (5) 30″ diameter light fixtures in low-wind or no-wind conditions, but not be able to support the same in substantial winds.
Therefore, with regard to temporary lighting, there is a real need in the art for an improved system which provides more flexibility and adjustability over a wide variety of situations.
Similar problems exist with regard to supporting or elevating other types of structures. For example, there is a need for a more versatile and flexible footing or base-support for vertical towers, scaffolds, and trusses that are not needed on a permanent basis.
It is therefore a principal objective of the present invention to provide an apparatus and method for a temporary spread footing that solves or overcomes the problems or deficiencies in the art. Other objects, features, and advantages of the present invention include an apparatus and method for temporary spread footing that:                1. Have a known resistance to overturning moment, but which are adjustable for variable attachments and conditions.        2. Have expandable dimensions and weight as compared to when configured for transport.        3. Allow interchangeable devices and add-on devices to be utilized.        4. Provide for a more efficient use of space and strength for a supporting base or footing.        5. Are adaptable and flexible for many situations and for moving, both at a location or site and to a different location or site.        6. Can be utilized with a variety of different vertical or elevated structures.        7. Are economical, efficient, and durable.        
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims.